My last GSD that I bought from a breeder also had a undescended testicle but the breeder informed me of this and he was discounted down to $1,200. Waited for a while for it to descend which it never did. When it came time for neutering it is now surgery they usually find it in the abdomen, ended up costing me $700,
If I were you I would confront the breeder about not only for a discount but the costs of the neutering.
Caleb Vom Adelhertz (Cutter) 6/18/05-1/26/14
Rebell vom Osangute-Land D.O.B. 10/15/13